Though it has been known for long that tumor cells can be self-sufficient for growth and survival, recent studies highlight the importance of interactions between the tumor and cells of the microenvironment, which can play a supportive role for tumor development and sustained growth. Thus a key to understanding cancer development and develop more effective therapeutics is to gain a complete picture of tumor cell interactions with cells of its environment. Cell-cell interactions are a complex process that can involve several surface molecules as well as molecules that are released from cells. To develop an understanding of cancer microenvironment biology, a new technique must be developed for the simultaneous analysis of multiple secretants and surface molecules from different cells that are interacting. Our long-tern goal is to develop a generic device for cell-cell interactions that can be custom tailored by the end user for analysis of a high number of secretants and cell surface molecules of choice. The objective of this application is the development of a new technology for the analysis of cell-cell communication, which will allow us to measure several secretants and surface molecules on single cells that are interacting with one another in real time. We will use this novel technology to investigate interactions between cells from chronic lymphocytic leukemia (CLL) patients and cells of their microenvironment. We chose to use CLL as model system for this application, because it is an easily accessible liquid tumor and our team member Dr. Kipps has more than 600 characterized samples in his tissue core that are available to us. Furthermore, we have data showing that CLL cells can release secretants that cause cells of their environment to acquire changes which in turn are of benefit for leukemia cell survival. Understanding what secretants are released by CLL cells will allow us to design novel therapeutic approaches. The specific aims of this application are: Construct and validate a novel tool that can make quantitative and qualitative measurements of many molecules at the same time on two different cell types that are interacting. Use the new device to investigate the communication process between CLL cells and cells of their environment. Research Design and Methods: Chemical and bioengineering methods will be used to build a collection of tiny chambers, that each holds one cell. These chambers will be connected with small tunnels that will allow molecules to pass through and thus enable the cells that are next to each other to communicate. Small detectors will be build into the chambers that will report what factors are released from the different cells. Cells will be distributed into the wells and secretants and surface molecules will be measured using a microscope. Recent evidence demonstrates that tumors can manipulate surrounding "non-tumor" cells which in turn play a critical role in tumor development and sustained growth. We will develop a new technology that will allow us monitor the complex communication process between cancer cells and cells of their environment in real time, for which there is currently no tool available. Understanding these interactions will reveal possible new approaches for therapeutic intervention.